Water-based drilling fluid additive containing talc and carrier

ABSTRACT

A drilling fluid additive is provided wherein the additive is manufactured by a method comprised of admixing colloidal solids such as talc with at least one carrier such as an oil or glycol to create a suspended mixture to thereby allow the colloidal solids to be pre-wet with the carrier; and then admixing copolymer beads to the suspended mixture.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an improved method of controlling the filtercake composition of a water-based drilling fluid by admixing colloidalsolids with at least one carrier, whereby the colloidal solids aresuspended in the carrier and then admixing polymeric beads to thesuspension prior to adding the suspended mixture to the drilling fluid.More specifically, the present invention relates to a drilling fluidadditive mixture manufactured by a method comprising of pre-wettingcopolymer beads and talc with oils or glycols to form a suspendedmixture and then adding the suspended mixture to the drilling fluid.

2. Description of the Related Art

New technology in drilling for oil and gas now includes horizontaldrilling. The horizontal drilling concept exposes more surface area ofthe producing zone than the conventional vertical drilling operations.For example, if a producing zone is fifty feet in thickness and avertical well is drilled through such a zone, then only fifty feet ofthe producing zone will be exposed for production. In contrast, ahorizontally drilled well may penetrate the producing sand or zone byone thousand feet or more. The amount or volume of oil or gas productionis directly proportional to the horizontal penetration in feet into theproducing sand or zone. In horizontal or directional drilling where thedrill pipe must bend in order to achieve the desired penetration intothe producing zone, friction becomes a major problem. The primary sourceof friction is directly related to the adhesion of the drilling assemblyto the wall cake which lines the drilled well bore. The capillaryattractive forces generated by the adhesion of the drilling assembly tothe wall cake are directly proportional to the amount or footage of thedrilling assembly exposed to the surface of the wall cake.

In horizontal or directional wells, many methods have been used in orderto reduce friction between the drilling assembly and the wall cake. Onesuch method would be to add a liquid lubricant to the drilling fluid inorder to reduce the coefficient of friction of the drilling fluid. Theseliquid lubricants include oils, such as hydrocarbon based oils,vegetable oils, glycols, etc. These liquid lubricants will usuallyreduce the coefficient of friction of the drilling fluid resulting in areduction of friction between the drilling assembly and the wall cake ofthe well bore.

When the liquid lubricant is added to the drilling fluid, it has severaloptions as to how it will react. One option is that the lubricantremains isolated and does not mix well with the drilling fluid. A secondoption is that the lubricant emulsifies with the water in the drillingfluid to form an oil-in-water emulsion. Still another option is the oilattaching itself to the commercial solids in the drilling fluid or tothe drilled cuttings or drilled solids. In certain circumstances, someof the liquid lubricant might be deposited or smeared onto the wall cakeof the well bore. The ideal scenario would be to have all of the liquidlubricant deposited on the wall cake.

Those experienced in drilling fluid engineering know that a thin, tough,pliable, and lubricious wall cake is most desirable. The integrity of awall cake is determined by several factors. The thickness of a wall cakeis directly proportional to the amount of liquid leaving the drillingfluid, and being forced into the wall of the well bore by hydrostaticpressure. The thickness of the wall cake is also determined by the typeand particle size of the solids in the drilling fluid. Particle SizeDistribution, or PSD is important to the wall cake integrity. Experts indrilling fluids also know that materials such as bentonite clay,starches, lignites and polymers are all used to build acceptable wallcakes. It is known in the prior art that various food grade vegetableoils are acceptable lubricants when used alone in water-based drillingfluids. It is also known in the prior art that round co-polymer beadswhen used alone in water-based drilling fluids function as a goodfriction reducer. However, much more is required to improve the wallcake integrity and lubricity of most well bores. In addition, there isno technology or process in the prior art that improves the lubricationor friction reducing capacity of the copolymer beads.

Furthermore, the solids control equipment used on the drilling rigstoday is far superior as to what was used 15 to 20 years ago. In thepast, drilling rig shale shakers would probably be limited to screensizes of about 20-40 mesh on the shakers. These coarser mesh screenswould allow pieces of shale and the drilled formation to pass throughthe shaker screens back into the drilling fluid and then recirculatedback down the well bore. As these larger than colloidal size particlesmake their way back up the well bore to the surface, the action of thedrilling assembly rotating within the well bore forces these largerparticles into the surface of the well bore. For example: a 20×20 meshshaker screen would allow a drilled cutting sized at 863 microns or0.0340 inches to pass through it and then the cutting would be returnedto the well bore and some of these 863 micron cuttings would eventuallybe embedded into the wall cake. This would give the wall cake surface atexture resembling that of coarse sandpaper. These larger particleswould allow the drilling fluid to channel and pass between the drillingassembly and the wall cake thereby reducing the negative effect of thecapillary attractive forces generated by the close contact of thedrilling assembly with the wall cake. The instances of the drillingassembly becoming stuck to the wall cake when less efficient solidscontrol equipment, such as shale shakers, was used much less than it istoday. The more efficient shale shakers today are a great improvementfor the drilling fluids but the instances of sticking the drillingassembly are higher. The reason for a higher rate of stuck drillingassemblies today could be blamed on cleaning the drilling fluid toefficiently. Today many drilling rigs utilize cascading shale shakers,which eventually pass the drilling fluid through 200 mesh or 74 micronscreens. This is very positive for controlling the percentage of drilledsolids in the drilling fluid but it also affects the texture or surfaceof the wall cake. The finer the solids on the surface of the wall cakeare, the greater the capillary attractive forces will be between thedrilling assembly and the wall cake.

The present invention provides a method of enhancing the surface of thewall cake. In order to accomplish this, the invention provides a method,which adds something to improve the texture of the surface of the wallcake, and then adds something to prevent large amounts of water fromleaving the drilling fluid then passing through the wall cake into theformation. The present invention also provides a carrier for thecolloidal solids and beads, which also acts as a lubricant for thedrilling fluid. The present invention further provides a process thatreduces the effect of capillary attractive forces between the drillingassembly and the wall cake, thereby reducing the tendency of thedrilling assembly to become stuck. In high angle directional wells wheredown hole motors are used to rotate the drill bit and the drill piperemains stationary, it is important that the drilling assembly can“slide” as the drilling bit cuts more holes. The resent inventionimproves the ability to “slide” while drilling as stated above.

SUMMARY OF THE INVENTION

In one embodiment, the present invention relates to a drilling fluidadditive mixture manufactured by a method comprising of admixingcolloidal solids with at least one carrier to create a suspendedmixture, the solids having an affinity for oils, esters, glycols andolefins, and the suspended mixture allowing the surface of the solids tobe pre-wet with the carrier prior to adding the mixture to a drillingfluid. In another embodiment, the drilling fluid additive mixturefurther comprises admixing copolymer beads to the suspended mixture. Instill another embodiment, the solids have an affinity for oils, esters,glycols and olefins. The carrier of the present invention also functionsas a lubricant.

In yet another embodiment, the beads have a specific gravity at fromabout 1.0 to about 1.5 and a size from about 40 microns to about 1500microns. In still yet another embodiment, the beads are comprised ofstyrene and divinylbenzene. In a further embodiment, the solids have asize range from about 2 microns to about 40 microns. In still a furtherembodiment, the solids are comprised of talc. For purposes of thisinvention, talc is a mineral, which is magnesium silicate. Talc isextremely hydrophobic and thus, repels water. Since talc has excellentwater repellant properties, it would be advantageous to have the surfaceof the walls of the base mud wall cake to be completely covered orcoated with talc.

In yet a further embodiment, the carrier consists essentially of oils,hydrocarbon oils, vegetable oils, mineral oils, paraffin oils, esters,glycols, cellulose and olefins. In still yet a further embodiment, thecarrier comprises soybean oil. In another further embodiment, thecarrier may be esters, fatty acids and glycols such as poly propyleneglycol. In a further embodiment, the carrier comprises oil and a glycolIn yet a further embodiment, the carrier consists essentially ofpolyanionic cellulose, polyanionic cellulose polymer, andcarboxymethylcellulose.

In still another further embodiment, the solids comprises from about 2%to about 50% of the additive mixture of the present invention. In yetanother further embodiment, the carrier comprises from about 50% toabout 98% of the additive mixture. In still yet another embodiment, thebeads comprises from about 2% to about 50% of the additive mixture.

In another embodiment, the present invention relates to a method ofmanufacturing a drilling fluid additive mixture, the method comprises:shearing colloidal solids with at least one carrier to create asuspended mixture to thereby allow the surface of the solids to bepre-wet with the carrier; and admixing copolymer beads to the suspendedmixture. In yet another embodiment, the solids and the beads having anaffinity for oils, esters, glycols and olefins. In another embodiment,the beads are sheared with the suspended mixture until a homogeneousmixture is formed.

In still yet another embodiment, the beads have a specific gravity atfrom about 1.0 to about 1.5 and a size from about 40 microns to about1500 microns. In a further embodiment, the beads are comprised ofstyrene and divinylbenzene. In yet a further embodiment, the solids havea size range from about 2 microns to about 40 microns. In still yet afurther embodiment, the solids are comprised of talc. In another furtherembodiment, the carrier consists essentially of oils, vegetable oils,mineral oils, paraffin oils, esters, glycols, cellulose and olefins. Inyet another further embodiment, the carrier comprises polypropyleneglycol. The combination of hydrophobic talc and polypropylene glycol asan additive, functions as an excellent plugging agent. For purposes ofthis invention, the term “plugging agent” is defined as a solid having aparticular size and shape so as to plug or seal off the surfacemicro-fractures of a porous sand, shale, or formation being drilled.

In still yet another embodiment, the solids comprises from about 2% toabout 50% of the additive mixture of the present invention. In yetanother further embodiment, the carrier comprises from about 50% toabout 98% of the additive mixture. In still yet another embodiment, thebeads comprises from about 2% to about 50% of the additive mixture.

In another embodiment, the present invention provides a method ofimproving the filter cake composition of a water-based drilling fluid,the method comprising: shearing colloidal solids with at least onecarrier to create a suspended mixture to thereby allow the solids to bepre-wet with the carrier; admixing copolymer beads to the suspendedmixture thereby allowing said beads to be pre-wet with the carrier;adding the suspended mixture to a water-based drilling fluid; and addingthe additive to a well bore.

In yet another embodiment, the solids and the beads have an affinity foroils, esters, glycols and olefins. In still another embodiment, thebeads have a specific gravity at from about 1.0 to about 1.5 and a sizefrom about 40 microns to about 1500 microns, and the beads are comprisedof styrene and divinylbenzene. In yet another embodiment, the solidshave a size range from about 2 microns to about 40 microns. In still yetanother embodiment, solids are comprised of talc. In a furtherembodiment, the carrier consists essentially of oils, hydrocarbon oils,vegetable oils, mineral oils, paraffin oils, esters, glycols andolefins. In still another further embodiment, the carrier comprisessoybean oil. In a further embodiment, the talc of the present inventionfunctions as a suspension agent and by making the talc oil wet, itbecomes more hydrophobic and thus, more effective. In another furtherembodiment, the combination of talc and oil functions as an excellentplugging agent.

In another embodiment, the solids comprises from about 2% to about 50%of the additive mixture, the carrier comprises from about 50% to about98% of the additive mixture, and the beads comprises from about 2% toabout 50% of the additive mixture.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the present invention. These drawings are incorporatedin and constitute a part of this specification, illustrate one or moreembodiments of the present invention, and together with the description,serve to explain the principles of the present invention.

FIG. 1 is a graph representing talc particle size versus volume inpercent; and

FIG. 2 is a graph representing the percent of beads suspended in oilversus the talc concentration as percent by weight of oil.

Among those benefits and improvements that have been disclosed, otherobjects and advantages of this invention will become apparent from thefollowing description taken in conjunction with the accompanyingdrawings. The drawings constitute a part of this specification andinclude exemplary embodiments of the present invention and illustratevarious objects and features thereof.

DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the invention that may be embodied in variousforms. The figures are not necessary to scale; some features may beexaggerated to show details of particular components. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a basis for the claims and asa representative basis for teaching one skilled in the art to variouslyemploy the present invention.

The present invention provides a process that includes selectingspecific materials having different particle sizes and then pre-wettingeach particle with an environmentally acceptable lubricant prior toadding these particles to the water-based drilling fluid. This processproduces much improved wall cake integrity and lubricity. The presentinvention also teaches that food grade vegetable oils are excellentcarriers for various solid friction reducers and wall cake enhancers.The present invention has also discovered that pre-wetting the roundcopolymer beads with a food grade vegetable oil prior to adding thecopolymer beads to the drilling fluid improves the lubrication orfriction reducing capacity of the copolymer beads. The other criterionis that the products and its components have to be environmentallyfriendly.

In accordance with the manufacturing process of the present invention,talc powder is sheared with an environmentally friendly oil or liquidlubricant, which repels water. The shearing should continue until eachorganophilic or hydrophobic talc particle is coated with the oil orliquid lubricant. In one embodiment, the talc powder most preferredwould be one with a particle size from about 1 micron to about 20microns and one which would produce a bell shaped curve having themajority of the particles in the 2 micron to 8 micron size, as shown inFIG. 1.

The polymeric beads of the present invention should be a solid particle,preferably round and have a specific gravity close to 1.0 and have asize from about 100 microns to about 900 microns. The beads must alsohave an affinity for oils, esters, olefins and glycols, etc. It wasdetermined that a copolymer bead manufactured by Dow Chemical comprisedof styrene and divinylbenzene would be acceptable.

The colloidal solids of the present invention should have a size rangeof 2-10 microns since tests have proven that this particle size willbridge sandstone having a permeability of 200 md. The solids must alsohave an affinity for oils, esters, olefins and glycols, etc. In oneembodiment, the solids are talc. The talc of the present invention alsofunctions as an excellent suspending agent in both oils and glycols.FIG. 1 depicts a graphical representation of the particle size of talcand Table 1, as set forth below, represents the result statistics forthe particle size for talc:

TABLE 1 Particle Size Statistics For Talc Dist. Type: Vol Concentration= 0.0136% Vol Density = 2.650 g/cub.cm Spec. SA = 0.5176 sq.m/g MeanDiameters: D (v, 0.1) = 2.40 um D (v, 0.5) = 5.28 um D (v, 0.9) = 11.68um D [4, 3] = 6.30 um D [3, 2] = 4.37 um Span = 1.760E + 00 Uniformity =5.495E − 01 Size Low (um) In % Size High (um) Under % 0.31 0.00 0.360.00 0.36 0.00 0.42 0.00 0.42 0.00 0.49 0.00 0.49 0.00 0.58 0.00 0.580.00 0.67 0.00 0.67 0.00 0.78 0.00 0.78 0.00 0.91 0.00 0.91 0.02 1.060.02 1.06 0.32 1.24 0.35 1.24 0.94 1.44 1.29 1.44 1.83 1.68 3.12 1.682.51 1.95 5.62 1.95 2.94 2.28 8.57 2.28 5.05 2.65 13.62 2.65 6.89 3.0920.51 3.09 7.96 3.60 28.47 3.60 7.81 4.19 36.29 4.19 8.89 4.88 45.184.88 9.49 5.69 54.67 5.69 9.05 6.63 63.72 6.63 8.60 7.72 72.33 7.72 7.619.00 79.94 9.00 6.35 10.48 86.29 10.48 5.02 12.21 91.31 12.21 3.70 14.2295.01 14.22 2.47 16.57 98.95 16.57 1.46 19.31 99.68 19.31 0.73 22.49100.00 22.49 0.27 26.20 100.00 26.20 0.05 30.53 100.00 30.53 0.00 35.56100.00 35.56 0.00 41.43 100.00 41.43 0.00 48.27 100.00 48.27 0.00 56.23100.00 56.23 0.00 65.51 100.00 65.51 0.00 76.32 100.00 76.32 0.00 88.91100.00 88.91 0.00 103.58 100.00 103.58 0.00 120.67 100.00 120.67 0.00140.58 100.00 140.58 0.00 163.77 100.00 163.77 0.00 190.80 100.00 190.800.00 222.28 100.00 222.28 0.00 258.95 100.00 258.95 0.00 301.68 100.00

The carrier of the present invention may be selected from differentoils, olefins, esters, fatty acids, cellulose and glycols. In anotherembodiment, the carrier may be synthetic oils, diesel oils, rice oils,cottonseed oils, corn oils, safalour oils, linseed oils, coconut oils,vegetable oils, mineral oils, and paraffin oils. In still anotherembodiment, the carrier is soybean oil. The oil coating on thehydrophobic talc particles enhances the plugging action of the talcacross or into micro fractures in sands, shale and other substances downhole.

In a further embodiment, the present invention relates to a method ofmanufacturing a drilling fluid additive whereby talc and copolymer beadsare added to soybean oil and mixed or sheared until each particle oftalc and copolymer bead is oil wet. A first sample was produced byaddition of 350 grams of soybean oil with 5 grams of talc and 100 gramsof polymer beads to the oil, and then mixing all the components for 10minutes using a waring blender. After blending, the mixture was placedin a beaker for observation. The mixture appeared homogeneous andinitially resembled buttermilk. After 5 minutes, the beads began tosettle. After one hour, all the beads settled to the bottom of thebeaker and some of the oil began separating from the mixture and clearoil was present at the upper portion of the beaker. After sittingovernight (10 hours later), the upper portion of the beaker was clearoil and the bottom portion was the talc, beads and oil. Pouring theclear oil off exposed that the beads had settled and packed tightlypreventing the beads from pouring out of the beaker. This sample couldnot be placed in a drum or tank for shipping because the beads wouldsettle and plug the drum or tank.

A second sample was produced by adding talc to the oil and eliminatingthe beads initially. It was discovered that the oil acceptedapproximately 40% by weight of talc. After sitting overnight, there wasno separation between the talc and the oil. At that point, smalladditions of beads were added to the above mixture. The addition of 2%by weight of beads to the talc/oil mixture was encouraging. The beadssettled slightly but did not pack off. As the concentration of the beadswas increased in the mixture, it was discovered that the beads remainedsuspended in the mixture. FIG. 2 depicts graphical representations ofthe talc concentration as percent (%) by weight of oil versus thepercent (%) of beads suspended in oil. FIG. 2 illustrates that as thetalc concentration as a percent (%) by weight of the oil increases, thesuspension qualities of the liquid oil increases. As FIG. 2 illustrates,the talc concentration of 20 percent by weight of the liquid oilsuspends 100 percent of the copolymer beads.

The second sample was then heated to 150 degrees Fahrenheit for 24 hoursand the copolymer beads remained suspended. The mixture was then cooledto 35 degrees Fahrenheit for 24 hours and the copolymer beads remainedsuspended. It was also discovered that the optimum concentration of thebeads was from about 20 percent to about 30 percent by weight of theoil, and the concentration of the talc should be around 20 percent byweight of oil. Although this sample appears to be the best, theconcentration may vary.

The specific examples throughout the specification will enable thepresent invention to be better understood. However, they are merelygiven by way of guidance and do not imply any limitations. Example 1conducted tests on a 9.9 pounds per gallon (ppg) water-based drillingfluid and Example 2 conducted tests on a 16.9 pounds per gallon (ppg)water-based drilling fluid. Example 3 conducted tests on the reductionof capillary forces in both the 9.9 ppg drilling fluid of Example 1 andthe 16.9 ppg drilling fluid of Example 2.

EXAMPLE 1

Test 1: Rheology & HPHT Results

In Example 1, a 9.9 pound per gallon water-based drilling fluid wastested for the (a) the compatibility of the drilling fluid—such asrheology; and the yield point and gels in particular; (b) the highpressure high temp fluid loss—HPHT; (c) the filter cake wt./gram; and(d) the filter cake thickness (in inches). Parameters were first testedon the base mud. By comparison, 2 percent (%) by volume of the oil, talcand the beads mixture was added to the base drilling fluid and mixed for5 minutes on a waring blender. In Test 1 & Table 2, the followingrheology and HPHT results were noted:

TABLE 2 Rheology & HPHT Results BASE & 2% BASE TALC MIXTURE % REDUCTIONDensity 9.9 PH Meter 10.3 600rpm 19 22 300rpm 11 13 200 rpm 8 10 100 rpm5 6  6 rpm 2 1  3 rpm 2 1 PV @ 120F 8 9 YP 3 4 Gels 10 sec/10 min 2/131/17 HPHT @ 200 Deg 12.0 8.0 33% F/ml Cake Wt./g 5.9 5.4 8% CakeThickness/inch 3/32 2/32 33% MBT/pbb 30 Solid/Oil/Water 10/00/90

The results of Example 1, Test 1 indicate the following: the talc, beadand oil mixture was very compatible with the mud rheology with onlyslight increases in yield point and gels. The HPHT fluid loss wasreduced from 12.0 to 8.0; a 33% reduction, which is excellent. The cakein weight in grams was reduced from 5.9 grams to 5.4 grams, an 8%reduction. The cake thickness in inches was reduced from {fraction(3/32)} to {fraction (2/32)}, a 33% reduction, which is also excellent.

EXAMPLE 1

Test 2: Dynamic Filtration

In Example 1, Test 2, the following dynamic filtration criteria weretested: (a) Fluid loss versus time; (b) Filter cake wt/gram; and (c)Filter cake thickness in inches. The dynamic filtration data of Example1, Test 2 is set forth in Table 3 below:

TABLE 3 DYNAMIC FILTRATION 5 Darcy, 50 Micron Filter Media 200 DegreesF., 600 rpm @ 1000 PSI for 60 Minutes Fluid Loss (ml) BASE & 2% TIME(Minutes) BASE TALC MIXTURE % REDUCTION Initial Spurt 1.5 trace 15 12.65.8 30 17.0 10.0 45 21.2 14.0 60 24.0 16.8 30% Cake Wt/g 10.7 5.8 46%Cake Thickness/Inch 3/32 2/32 33%

The results of Example 1, Test 2 are as follows: after 60 minutes, thedynamic fluid loss was reduced from 24.0 ml to 16.8 ml, a 30% reduction,which is excellent. The cake weight in grams was reduced from 10.7 gramsto 5.8 grams, a 46% reduction, which is also excellent. The cakethickness was reduced from {fraction (3/32)} to {fraction (2/32)}, a 33%reduction, which is excellent.

EXAMPLE 1

Test 3: Lubricity Test

Table 4 below shows the test results of the lubricity of the additive astorque is applied.

TABLE 4 LUBRICITY TEST @ 60 rpms Co-efficient of Friction of Water (0.33− 0.36) = 0.33; i.e. reading at 150 inch pounds is 33 Lubricity Reading(electric current required to sustain 60 rpm at applied torque) AppliedTorque/ BASE & 2% Inch Pounds BASE TALC MIXTURE % REDUCTION 100 10 11150 16 16 200 21 21 300 31 28 400 44 37 500 66 50 600 80 65 19%

The lubricity results of Example 1, Test 3 indicate an improvement inlubrication was about 19% at the 600 reading on the lubricity tester.

EXAMPLE 1

Test 4: Texture of Dynamic Filter Cake Surfaces

The texture of the filter cake surfaces and the surfaces of the base mudwere also tested. The results were as follows: the texture of thesurface of the base mud was extremely smooth and shinny. The texture ofthe Dynamic Filter Cake Surface of the base mud treated with 2% byvolume of the talc, bead and oil mixture was shinny and the copolymerbeads could be seen impregnated in the cake as well as protruding on thesurface of the cake.

EXAMPLE 2

Test 1: Rheology & HPHT Results

In Example 2, a 16.9 pound per gallon water-based drilling fluid wastested for the (a) the compatibility of the drilling fluid—such asrheology; and the yield point and gels in particular; (b) the highpressure high temp fluid loss—HPHT; (c) the filter cake wt./gram; and(d) the filter cake thickness (in inches). Parameters were first testedon the base mud. By comparison, 2 percent (%) by volume of the oil, talcand the beads mixture was added to the base drilling fluid and mixed for5 minutes on a waring blender. In Example 2, Test 1, the followingrheology and HPHT results were noted in Table 5 below:

TABLE 5 Rheology & HPHT Results BASE & 2% BASE TALC MIXTURE % REDUCTIONDensity 16.9 PH Meter 10.4 600 rpm 53 56 300 rpm 30 32 200 rpm 22 25 100rpm 13 15  6 rpm 2 3  3 rpm 1 2 PV @ 120 F. 23 24 YP 7 8 Gels 10 sec/10min 4/19 5/27 HPHT @ 300 Deg 15.0 13.2 12% F./ml Cake Wt./g 27.2 18.731% Cake Thickness/inch 6/32 4/32 33%

The results of Example 2, Test 1 indicate the following: in Test 2,Table 5, the talc, beads and oil mixture was very compatible with themud rheology with little change points and gel. The HPHT fluid loss wasreduced from 15.0 to 13.2, a 12% reduction, which is somewhat less thanexpected. The cake weight in grams was reduced from 27.2 grams to 18.7grams, a 31% reduction, which is a very good result. The cake thicknesswas reduced from {fraction (6/32)} to {fraction (4/32)}, a 33%reduction.

EXAMPLE 2

Test 2: Dynamic Filtration

In Example 2, Test 2, the following dynamic filtration criteria weretested: (a) Fluid loss versus time; (b) Filter cake wt/gram; and (c)Filter cake thickness in inches. The dynamic filtration data of Example2, Test 2 is set forth in Table 6 below:

TABLE 6 DYNAMIC FILTRATION 10 Darcy, 35 Micron Filter Media 300 DegreesF., 600 rpm @ 1000 PSI for 60 Minutes Fluid Loss (ml) BASE & 2% TIME(Minutes) BASE TALC MIXTURE % REDUCTION Initial Spurt 1.0 0.5 15 25.217.6 30 38.0 25.0 45 46.0 31.4 60 53.2 36.0 32% Cake Wt/g 91 62 32% CakeThickness/Inch 18/32 12/32 33%

The results of Example 2, Test 2, Table 6 are as follows: after 60minutes, the dynamic fluid loss was reduced from 24.0 ml to 16.8 ml, a32% reduction, which is an excellent result. The cake weight in gramswas reduced from 91 grams to 62 grams, a 32% reduction, which is a verygood result. The filter cake was reduced from {fraction (18/32)} to{fraction (12/32)}, a 33% reduction, which is also an excellent result.

EXAMPLE 2

Test 3: Lubricity Test

Table 7 below shows the test results of the lubricity of the additive astorque is applied.

TABLE 7 LUBRICITY TEST @ 60 rpms Co-efficient of Friction of Water (0.33− 0.36) = 0.33; i.e. reading at 150 inch pounds is 33 Lubricity Reading(electric current required to sustain 60 rpm at applied torque) AppliedTorque/ BASE & 2% Inch Pounds BASE TALC MIXTURE % REDUCTION 100 14 9 15023 12 200 30 15 300 46 20 400 60 23 500 76 25 600 92 28 70%

The lubricity results of Example 2, Test 3 indicate an improvement inlubrication was about 70% at the 600 reading on the lubricity tester,which is an excellent result.

EXAMPLE 2

Test 4: Texture of Dynamic Filter Cake Surfaces

The texture of the filter cake surfaces and the surfaces of the base mudwere also tested. The results were as follows: the texture of thesurface of the base 16.9 ppg mud was smooth and shinny. The texture ofthe Dynamic Filter Cake surface of the base mud treated with 2% byvolume of the talc, bead and oil mixture was shinny and the copolymerbeads could be seen impregnated in the cake as well as protruding on thesurface of the cake.

EXAMPLE 3

Reduction in Capillary Attractive Forces of Examples 1& 2

In Example 3, the (dynamic) filter cake of the base mud was placed on aflat surface and a piece of glass ¼ inch thick and four inches squarewas placed flat on the surface of the base mud filter cake and allowedto sit for thirty minutes. An attempt was then made to lift the glassfrom the filter cake. As the glass plate was lifted, the filter cakefollowed and it was as though the filter cake was glued to the glass.

The (dynamic) filter cake of the base mud to which 2% of the additive ofthe present invention was added was placed on the flat surface and thesame process discussed above was duplicated. It was found that the pieceof glass easily separated from the filter cake surface, which wastreated with the additive of the present invention. The results showthat the additive mixture of the present invention definitely reduced,if not, eliminated the capillary attractive forces of the wall cake.

Since the above tests were conducted in open air on the counter top, itwas determined that the same tests should be conducted while totallysubmerged in the drilling fluid. In running the same tests with thefilter cake and the 4 inch piece of glass completely submerged in thedrilling fluid, it would be concluded that no air would be present inthe filter cake or the glass surface and such a test would resemble awellbore filled with drilling fluid. This test results were as follows:the glass plate stuck more firmly to the submerged water-based mud wallcakes than it did in open air; and the glass plate would not stick tothe wall cakes of the water-based muds, which were treated with the 2%by volume of the drilling fluid additive of the present invention.

Numerous modifications and variations of the present invention arepossible in light of the above teachings. It is therefore to beunderstood that within the scope of the attendant claims attachedhereto, this invention may be practiced otherwise than as specificallydisclosed herein.

What is claimed is:
 1. A drilling fluid additive mixture manufactured bya method comprising of: admixing talc with at least one carrier tocreate a suspended mixture, said suspended mixture allowing the surfaceof said talc to be pre-wet with said carrier, said carrier beingselected from a group consisting of oils, glycols, esters, olefins andmixtures thereof, and admixing copolymer beads to said mixture prior toadding said mixture to a drilling fluid.
 2. The drilling fluid additivemixture of claim 1 wherein said beads have a specific gravity at fromabout 1.0 to about 1.5 and a size from about 40 microns to about 1500microns.
 3. The drilling fluid additive mixture of claim 1 wherein saidbeads are comprised of styrene and divinylbenzene.
 4. The drilling fluidadditive mixture of claim 1 wherein said talc has a size range fromabout 2 microns to about 40 microns.
 5. The drilling fluid additivemixture of claim 1 wherein said carrier consist essentially of oils,hydrocarbon oils, vegetable oils, mineral oils, paraffin oils, syntheticoils, diesel oils, esters, glycols, cellulose and olefins.
 6. Thedrilling fluid additive mixture of claim 1 wherein said carriercomprises soybean oil.
 7. The drilling fluid additive mixture of claim 1wherein said talc comprises from about 2% to about 50% of said additivemixture.
 8. The drilling fluid additive mixture of claim 1 wherein saidcarrier comprises from about 50% to about 98% of said additive mixture.9. The drilling fluid additive mixture of claim 1 wherein said beadscomprises from about 2% to about 50% of said additive mixture.
 10. Amethod of manufacturing a drilling fluid additive mixture, said methodcomprising: shearing talc with at least one carrier to create asuspended mixture to thereby allow the surface of said talc to bepre-wet with said carrier, said carrier being selected from a groupconsisting of oils, glycols, esters, olefins and mixtures thereof; andadmixing copolymer beads to said suspended mixture.
 11. The method ofclaim 10 wherein said beads have a specific gravity at from about 1.0 toabout 1.5 and a size from about 40 microns to about 1500 microns. 12.The method of claim 10 wherein said beads are comprised of styrene anddivinylbenzene.
 13. The method of claim 10 wherein said talc has a sizerange from about 2 microns to about 40 microns.
 14. The method of claim10 wherein said carrier comprises polypropylene glycol.
 15. The methodof claim 10 wherein said talc comprises from about 2% to about 50% ofsaid additive mixture.
 16. The method of claim 10 wherein said carriercomprises from about 50% to about 98% of said additive mixture.
 17. Themethod of claim 10 wherein said beads comprises from about 2% to about50% of said additive mixture.
 18. A method of improving the filter cakecomposition of a water-based drilling fluid, said method comprising:shearing talc with at least one carrier to create a suspended mixture tothereby allow said talc to pre-wet with said carrier, said carrier beingselected from a group consisting of oils, glycols, esters, olefins andmixtures thereof; admixing copolymer beads to said suspended mixturethereby allowing said beads to be pre-wet with said carrier and shearinguntil a homogeneous mixture is formed; adding said suspended mixture toa water-based drilling fluid; and pumping said additive into a wellbore.
 19. The method of claim 18 wherein said beads have a specificgravity at from about 1.0 to about 1.5 and a size from about 40 micronsto about 1500 microns, said beads are comprised of styrene anddivinylbenzene.
 20. The method of claim 18 wherein said talc has a sizerange from about 2 microns to about 40 microns.
 21. The method of claim18 wherein said carrier comprises oil and glycol.
 22. The method ofclaim 18 wherein said talc comprises from about 2% to about 25% of saidadditive mixture, said carrier comprises from about 50% to about 96% ofsaid additive mixture, and said beads comprises from about 2% to about25% of said additive mixture.
 23. A drilling fluid additive comprising:talc, copolymer beads and at least one carrier, said carrier beingselected from a group consisting of oils, glycols, esters, olefins andmixtures thereof.
 24. The drilling fluid additive of claim 23 whereinsaid beads have a specific gravity of from about 1.0 to about 1.5 and asize from about 40 microns to about 1500 microns, said beads arecomprised of a material selected from a group consisting of styrene,divinylbenzene and mixtures thereof.
 25. The drilling fluid additive ofclaim 23 wherein said talc comprises from about 2% to about 25% of saidadditive mixture, said carrier comprises from about 50% to about 96% ofsaid additive mixture, and said beads comprise from about 2% to about25% of said additive mixture.